The present invention relates to an exhaust gas turbine for a turbocharger of an internal combustion engine with a turbine wheel arranged in a turbine housing including inlet passages for admitting exhaust gas to the turbine wheel and a flow control arrangement comprising a vane ring slidably supported around the turbine wheel so as to be movable by an operating mechanism into, and out of, the inlet passages for controlling the exhaust gas flow to the turbine wheel.
DE 196 45 388 A1 discloses such an exhaust gas turbine wherein a guide vane sleeve is arranged between a spiral inlet passage and a turbine wheel so as to be movable axially into, and out of, an annular space in the turbine housing. At its free front end, the guide vane sleeve includes a cover ring which, in the retracted position of the guide vane sleeve, covers an annular space between the turbine housing and an inner guide structure for the guide vane sleeve. In the extended sections of the guide vane sleeve, the cover ring reduces the axial length of the annular space and forms a flow resistance in the form of a sharp-edged step in the contour of the spiral inlet passage. The step generates turbulence in the inlet flow which results in an efficiency loss of the turbine.
DE 31 51 414 A1 discloses an exhaust gas turbine for a turbocharger of an internal combustion engine with a turbine housing having an inlet passage and a turbine wheel disposed in the turbine housing. In the area of the outer circumference of the turbine wheel, a guide vane sleeve is slidably supported and is movable by an operating mechanism into, and out of, an annular space formed in the turbine housing around the turbine wheel. The operating mechanism comprises an operating cylinder which is mounted onto a support structure which is connected in the area of the outer circumference of a cylindrical inner part co-axially surrounding the turbine outlet and which is directly or indirectly connected to the guide vane sleeve.
DE 198 16 645 A1 discloses an exhaust gas turbine for a turbocharger of an internal combustion engine with a turbine wheel disposed in a turbine housing including an inlet channel guiding the exhaust gas to the turbine wheel. A guide vane sleeve extends in an annular space around the turbine wheel and is axially movable into and out of the annular space by means of a piston rod and a pneumatic cylinder.
The operating mechanism however is relatively complicated and expensive.
It is the object of the present invention to provide an operating mechanism for the adjustment of the guide vanes which is simple, inexpensive and reliable.